When setting visibility of progress bar type spinner the app crashes

Question

I am building an app that open a webview and while it is opening the webpage i want to show a spinner type progressbar but when i change the visibility using setvisibility() the app crashes .

Here is my Activity code:

public class MainActivity extends Activity {

    WebView website;
    ProgressBar pro;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        pro= (ProgressBar) findViewById(R.id.progress);
        setContentView(R.layout.activity_main);

        website = (WebView) findViewById(R.id.website);
        website.setWebViewClient(new WebViewClient());

        WebSettings webSettings = website.getSettings();
        webSettings.setJavaScriptEnabled(true);
        website.loadUrl("http://www.google.com");
        website.setWebChromeClient(new WebChromeClient() {

            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                //change your progress bar
                if(pro.getVisibility()==view.VISIBLE){
                   pro.setVisibility(view.INVISIBLE);
                }
                else {
                    pro.setVisibility(view.VISIBLE);
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode ==KeyEvent.KEYCODE_BACK) && website.canGoBack()) {
            website.goBack();
            return true;
        }
        else{
            finish();
        }
        return super.onKeyDown(keyCode, event);
    }

}

---

Log cat

3:08:57 PM Gradle build finished in 9 sec 3:22:44 PM Gradle build finished in 35 sec 3:24:41 PM Gradle build finished in 7 sec 3:24:44 PM Session 'app': running 3:26:47 PM Gradle build finished in 6 sec 3:26:49 PM Session 'app': running 3:30:31 PM Gradle build finished in 13 sec 3:30:34 PM Session 'app': running 3:38:54 PM Gradle build finished in 9 sec 3:39:02 PM Session 'app': running 3:39:02 PM Session 'app': running 3:39:04 PM Gradle build finished in 10 sec 3:39:06 PM Session 'app': debugger connected 3:57:21 PM Gradle build finished in 11 sec 3:57:24 PM Session 'app': running 11:16:08 AM Gradle build finished in 37 sec 11:16:11 AM Session 'app': running 11:52:39 AM Gradle build finished with 2 error(s) in 11 sec 11:55:00 AM Gradle build finished in 28 sec 11:58:45 AM Gradle build finished in 18 sec 11:59:04 AM Gradle build finished in 6 sec 11:59:09 AM Session 'app': running 3:51:43 PM Gradle build finished in 25 sec 3:53:31 PM Gradle build finished in 40 sec 3:53:33 PM Session 'app': running 3:56:04 PM Gradle build finished in 2 sec 3:56:07 PM Session 'app': running 3:56:51 PM Gradle build finished in 2 sec 4:04:03 PM Gradle build finished in 6 sec 4:04:07 PM Session 'app': running 4:04:54 PM Gradle build finished in 4 sec 4:04:56 PM Session 'app': running 4:05:34 PM Gradle build finished in 3 sec 4:05:37 PM Session 'app': running 4:08:51 PM Gradle build finished in 32 sec 4:09:00 PM Session 'app': running 4:13:42 PM Gradle build finished in 36 sec 4:13:44 PM Session 'app': running 4:50:31 PM Gradle build finished in 14 sec 4:50:36 PM Session 'app': running 5:04:19 PM Gradle build finished in 10 sec 5:04:22 PM Session 'app': running

Answer 1

You should call:

setContentView(R.layout.activity_main);

before calling:

pro = (ProgressBar) findViewById(R.id.progress);

Because you have to set a view before looking for a child subview.